Hiya.
So if you come in via Ratuk up towards Det at FL80 you're going to get right in the teeth of the LC outbounds and depending on the pressure then be in the way of LAM so you are likely to get descent to be 4000' at DET for Thames to then get you through. LAM Thames and LL are unlikely to want you cruising through east of LAM at min stack or min stack+1000 so South won't have much option.
If you come via DVR it will be similar, depending on inbounds via GODLU for City and Biggin, and also the MC ins which we have to get to FL80 at ATSAP and under the LC traffic so again you will likely get descent.
You can file to go through BIG towards CPT and I'll go back to my first list!!! Some days you will be lucky and go right through and get descent at CPT but more likely you will either be sent the "long way round" south of the Heathrow stacks across Gatwick but if outbounds from KK are busy (!) you may even get the "very long way round" south of KK and then back up so adding significant miles to your trip.
Inbound to Denham you are entitled to file in to work LL approach so routing on a BIG star and then subject workload they will take you and descend you over the top of LL and usually (I think... not an expert on this one) hand you off to Northolt approach.
To be honest, far from "Dump it on Thames" They are often the best placed to give you a service.... and very helpful they are too, in what has become an increasingly busy set of 'minor' airfields.
Best times to fly? Sat pm and Sun am with LC closed!
If you'd like a particular option then ask and we'll do what we can, but be prepared for a longer routing/early descent...
Hope that helps.
Cheers,
Northerner
